On Feb 28, 5:42 am, wrote:
How do I calculate the 6 month annualized % change for this series
1/1/59 286.6
2/1/59 287.7
3/1/59 289.2
4/1/59 290.1
5/1/59 292.2
6/1/59 294.1

=(294.1/286.6)^(12/5) - 1

or

=(294.1/286.6 - 1)*12/5

The right answer depends on whether or not you expect the growth to
compound (first formula).

You cannot do "^2" or "*2", as you might expect, because you really
have only 5 months of changes. It would be great if you have the data
for 12/1/58. Then substitute its value for 286.6 in the denominator
and use "^2" or "*2".